Flexible key form for forming recesses in concrete structures



F April 22, 1952 R. M. JAMES 2,593,456

FLEXIBLE KEY FORM FoR FCRMING RECEssEs 1N CONCRETE STRUCTURES I Filed March 29, 1949 EQ2 J9 i 20h13 f1 13 7% y Z Patented Apr. 22, 1952 UNITED STATES PATENT OFFICE FLEXIBLE KEY FORM FOR FORMIING RE- --CESSES IN CONCRETE vSTRUCTURES Robert,lYIavxwell` J ames, Buffalo, N. Y.

Application March 29, 1949, Serial No. 84,062

13 Claims.

l kThis invention relates to a exible tool device suitable for use in .construction work in connectionwith therformationof undercut nichesorA keys in concrete wallsand forms. As such,this

invention relates generally to mold apparatus Each of the key forms constructed in accordance with my invention is shaped in the form of a substantially circular disk and is provided with a plurality of radially extending grooves on one face thereof. A circumferential, angularly inclined lip is formed on the other face which terminates in an annular recessed hinge area.

o A circular suction cup portion integrally formed rin the disk and lying in concentric relationshipV with the lip portion is also provided.

A plurality of key forms having these characteristics may be selectively positioned to project outwardly upon the liner surface of a mold form and may be held thereupon by normal atmospheric air pressure. i

A mold form equipped with key forms having the aforementioned characteristics receives the dock walls, .break waters, bridges and dams and more intricate. Aconstructions in ferro-plastic for iloors, columns, buildings, arches, domes, towers, water tanks, pontoons, foundation cylinders, tiles, open-work jetties, and many other purposes.A Concrete as a lbuilding material is distinguished by the facility with which lit canV be deposited and molded while in a plastic condition into almost any desired shape.

"It is usually necessary, therefore, to provide suitable mold forms for receiving the plastic concrete aggregate tliereagainst, and these molds are,l of course', constructed to deneany desired moldingpattern. j A i Heretofora- 1 construction workers vhave experienced many' diliculties.- Plaineor mass concrete `is not readily adaptable tov arichitectural treatment, tyetfitzcan beF used wherever vmassive masonry or,A brick work is suitable. Thus, theconcrete mold formsprovided for the use of the building tradesmen in the past have usually consisted largely of simple `box-like forms heldtof gether by'metal straps or the like. T Y

A hardened Aconcrete form resulting from casting aplastic vconcrete.' aggregate in such ,a mold defines a uniformly flatfsurface,v which'` must of necessity be augmented or adapted forthe use of special anchoring devices if it is to be employed as a foundation for, plaster, acoustic tile, marble or slate slabs, vor othentypes of finishing material as may be desired in various types of building construction. l A

i The presentinvention contemplates the provision of flexible key forms made of a molded resilient material such as Vhard rubber or the like, which may bealiixed tothe linersurface of mold formsf Iwhereby concrete-1 forms having un-ique Structural-radvantasesmaybefprodugedz 1 plastic concrete aggregate in surrounding molded proximity'with the projecting key forms, thereby shaping the surface of the ultimate hardened concrete form to conform to the pattern dened by the mold liner surface.

By pulling the mold form away from the hardened concrete form, the flexible key forms carried thereby may be easily withdrawn from the concrete, thereby producing a plurality of unique dovetailed niches or undercuts in the concrete surface which may be utilized for various and vsundry purposes. Easy removal of the key forms -is facilitated by the unique features incorporated in the key forms whereby a hinging action occurs which permits the forms to contract radially `through the areas defined by the radial grooves.

An'object of this invention is to provide a flexible key form suitable for attachment to the liner face of mold forms without the use of separate fastening means, whereby niched surfacesmay be produced in a hardened plastic conglomerate.

Another object of this invention is to provide an improved mold form equipped with flexible key forms suitable for supporting metal reinforcing members during the casting of ferro-concrete structures without the necessity of employ- Figure r1 is @partial elevational viewshowing the liner surface of a mold form constructed in accordance with a method contemplated by this invention;

Figure 2 is a cross-sectional view partly broken away showing a key form as provided in the instant invention aixed to a liner surface of a mold form;

Figure 3 is a plan View of a key form constructed in accordance with the principles of my invention;

Figure 4 is a cross-sectional view taken on a diametric axis of the key form shown in Figure 3 and shows the details of construction and arrangements of parts of the key form prior to attachment to a liner surface of a mold form;

Figure 5 is a bottom view of the key form shown in Figure 3;

The lip I5 is angularly inclined and extends `inwardly toward the center of the key form IU in such a manner as to substantially define the surface configuration of a cone.

The lip I5 terminates in an inwardly disposed annular recess or hinge area I6 (Figure 4). A central hub or suction cup II is formed in such a'manner as to extend away from the annular recess or hinge area I6 and lie in concentric relationship with the lip I5. The lip of the hub or suction cup I'I is circular in form and surrounds a depressed cup portion I8.

It will be noted that the plane developed by the circular lip of suction cup II normally lies slightly below the plane developed by the circu- ,Q lar lip I5 at its outermost extremities.

Figure 6 is a partial cross-sectional View showing a key form attached to the liner surface of a mold form and surrounded by a plastic aggregate such as concrete or the like;

Figure 7 is a partial cross-sectional view showing how the key forms illustrated in Figure 6 may be remove-d from the concrete conglomerate after hardening;

Figure 8 is a partial cross-sectional view showing the details of the undercut niche or recess resulting in the hardened conglomerate after the` removal of the key form shown in Figures v6 and '7;

Figure 9 is a partial cross-sectional View showing an alternative method of fastening the key form of the present invention to the liner surface of a mold form.

As shown on the drawings:

Referring first to Figures 3, 4 and 5, a key form is indicated generally at I. Each key form I0 comprises a substantially circular disk made of a flexible material. It is highly desirable that the material of which the disks are made-have comparatively rigid characteristics and, to that end, each of the key forms I0 may be preferably formed of molded oil-resistant rubber such as neoprene or the like.

A plurality of V-shaped grooves II are formed in the upper face and l.on the outer peripheral portion of the form I in spaced radial relationship to one another. The apices of the V-shaped grooves I I lie substantially on a common circular axis concentric with the outer periphery of the form I9, but lying on an inner portion toward the center of the form I0.

The upper surface of the form I0 may also be dished out to forni a slight circular recess as at I2.

It will be noted that due to the provision of the radially spaced Vshaped grooves II, the upper surface of the key form I2 is characterized by a plurality of projecting tongue portions I3 which .are likewise radially spaced in relation to one another. Thus, as may be seen in Figure 3, the plan view of the key form I9 resembles a rosettelike configuration.

The tongue portions I3 are provided with suitably rounded corners and are adapted to be angularly inclined in such a manner as to taper inwardly toward the under portion of the key form I9. The form I0 therefore takes the configuration of a substantially circular disk skived along its peripheral edge as at i4 to form a truncated c conical segment.

As may be seen in greater detail on Figures 4 and 5, the inclined portions I4 of the tongues I3 terminate in a circular lip I5 of smaller diameter than the outer diameter of the key form I0,

Referring now to Figure 2, a key form I0 is shown applied to the liner surface of a typical rigid mold form I9. When a form I0 is first positioned on the liner surface the lip I5 effectively contacts the liner surface and will yield against the resilience of the form I0 to produce a tight edge with the liner surface. This characteristic is highly desirable inasmuch as a strong niche lip may be formed in the concrete undercut in the locale between the mold form I9 and the key form l0. It will also be apparent that the snug relationship between the mold form I9 and the key form Il) operates to prevent concrete leakage into the suction cup area.

By firmly pressing the key form ID onto the mold form I9, the inwardly disposed suction cup I'I is brought into contact with the liner surface and the air normally contained in the cavity of the recess I8 will be expelled.

It should be apparent that the suction cup II operates in a conventional manner to hold the key form I0 firmly in place upon the liner surface by virtue of the atmospheric air pressure exerted upon the outer surface of the suction cup I1 in thel direction of the recess I8 andthe mold form I9.

It will be noted that when the key form I0 is firmly afxed to the mold form I9, as shown in Figure 2, the upper surface of the key form I0, which normally describes a slightly arcuate configuration (Figure 4), assumes a substantially planar surface parallel to the liner surface. Because of these characteristics, a plurality of key forms affixed to a liner surface of a mold form presents a uniform planar surface spaced a predetermined distance from the liner surface corresponding to the thickness of the key forms in such a manner as to present an effective supporting means for reinforcing metals used in ferroconcrete structures. It will be apparent that reinforcing metal may be laid across the various key forms and the plastic concrete aggregate may subsequently be molded around such reinforcement without the employment of additional supporting chairs as have been required heretofore.

Referring now to Figure 6, the key form I0 is shown affixed to the mold form I9 and surrounded by a plastic aggregate 20, such as concrete or the like. It will be noted that the suction cup area interiorly of the lip I5 is free of concrete leakage despite the molded proximity of the plastic aggregate 20 to the liner surface of the mold form I9 at the locale of the key form I0.

Referring now to Figure 7, the mold form I9 is shown in the process of removal from the plastic aggregate which, it is assumed, has hardened into a conglomerate 20a such as a concrete form. The annular recess I6 forms a hinge area whichprovides for the necessary flexibility drawn." The suction'cup of course, remains firmly affixed to the form` I9.

fReferring now toligure 8, it will be evident that upon' the removal of the key form I9 from the hardened plastic conglomerate 20a, an undercut. niche or key 2| will be left in the `surface of lliner surface ofthe mold the conglomerate 20a corresponding to the projecting configuration definedby each key form I0 upon the liner surface of the mold form |9.

The niches 2| leave a wall face on the conglomerate 20a whichv is smooth and without projecting interferencesv and which is characterized by one or more `dovetailed recesses 22 shaped to correspond tothe tongues I3 of the form |0-and af plurality'of radiall 4fins 23 which correspond to theV shape of the V-shaped grooves |I in the key-form4 IIJ.` The radial fins 23 effectively reinforce the'lip of each niche 2| and add considerably to the anchorage strength potential available in the use` of such a dovetailed recess.

wEach niche or key 2| may bev used for a variety of purposes. v K filledlwith'plastic wood or a similar nail-holding material to provide positive anchorage for plaster grounds. A niche adapted in such a manner would also furnish a positive method of supporting acoustical tile.A

By employing a supplementary anchor device vof pla-ster, kacoustic tile, or finishing material such as marble and slate.

It will also be apparent to those versed in the art Athat I have described a new and improved key form device suitable for attachment tothe linersurface of mold forms and ladapted to pro- "du'ce useful and decorative undercut niches or lkeys in hardened concrete surfaces.

'Although I have resorted to detail in the de- 5- scription of my invention for the sake of clarity, vit is contemplated that many modifications may be suggested by those skilled in the art without departing from the essential spirit of my invenvf-tion. I do not wish to'be limited, therefore, by

the specific embodiments herein shown by way of illustration.

I claim as my invention:

1. A flexible key form defining a disk having 'v a plurality of spaced radial tongues and grooves on one face thereof, a circular lip of smaller diarneter on the other face thereof and an integral the locale between said lip and suction cup For example, the niches Ycould be portions.

2. A lflexible key form defining a disk, said disk comprising an integral construction having a plurality of radially spaced tongues and grooves on one face thereof, a central Vhub defining a sucshapedvto `conform to the configuration of the niche 2|,'the niche could be filled with mortar or plaster of Paris after the anchor devices are inserted therein, and such devices could be used c for anchoringl marble, slate, or other slab-like finishing material.

As maybe seen on Figure 1, a liner surface of surface of a mold form I9 by the use of a suction cup I1 and without the use of additional adhesives or plastic means, it will be apparent to those versed in the art that the instant key formy 4Q lying substantially at the base of said skived peripheral edge, a recessed portion interiorly of said lip and on said other face, a central hub defining tion cup on the other face thereof, an annular recess surrounding said hub, and an angularly 'inclined lip portion extending outwardly away from said recess.

3. A flexible key form substantially in the form of a disk, said disk comprising an integral construction having a plurality of spaced grooves on one face thereof, the portions of said disks between said grooves dening a skived peripheral edge, a circular lip on the other face of said disk a suction cup extending into said recessed portion, and an annular recessed hinge area at the base of said hub.

4. A'fiexible key form substantially in the form of a disk, said disk defining in an integral construction a plurality of spaced grooves on one face thereof, a skived peripheral edge along the portions of said disk between said grooves, a circular lip on the other face thereof lying substantially at the base of said skived peripheral edge, a recessed portion interiorly of said lip and on said other face, a central hub forming a suction cup extending into said recessed portion but terminating short of the plane developed by 'said lip, and an annular recessed hinge area at I0 is readily adaptable to the use of supple-"-` mentaryfastening material such as adhesives or.

thelike for the purpose of effecting a permanent bond between each key form I0 and the liner surface on a mold form I9.

so jf By Yway of illustration, therefore, Figure shows a mold form I9 to which is afxed a key( form I Il.v A suitable adhesive 25 is shown as being placed on the lip of the suction cup l1. Thus, the key form I0 is firmly bonded to the liner surface of the mold form I9.

It will be apparent to those versed in the art niches or keys which may be used for anchorage the base of said hub.

' 5. A flexible key form for use with a rigid mold form defining a fiat liner surface, comprising, a disk having a plurality of spaced radial tongues Aand grooves on one face thereof, a circular lip of smaller diameter on the other face thereof v'and an integral suction cup formed interiorly of said lip portion, said key form further defining a recessed hinge area in the locale between said lip and suction cup portions.

6. A flexible key form for use with a rigid mold form defining a fiat liner surface, comprising, a disk, said disk comprising an integral construction having a plurality of radially spaced tongues and grooves on one face thereof, a cen- 'tral hub defining a suction cup on the other face thereof, an annular recess surrounding said hub, and an angularly inclined lip portion extending outwardly away from said recess.

7. A flexible key form for use with a rigid mold form dening a flat liner surface comprising a disk-like form, said disk defining in an integral construction a plurality of spaced grooves on one face thereof, a skived peripheral edge along the portions of said disk between said grooves, a circular lip on the other face thereof lying substantially at the base of said skived peripheral edge, a recessed portion interiorly of said lip and on said other face, a central hub defining a suction cup extending into said recessed portion, and an annular recessed hinge area at the base of said hub.

8. A exible key form for use with a rigid mold form defining a at liner surface and shaped substantially in the form of a disk, said disk comprising in an integral construction an upper face defining a plurality of spaced grooves,

the portions of said disk between said grooves defining a skived peripheral edge, a circular lip on the other face thereof lying substantially at thevbase of said skived peripheral edge, a recess portion interiorly of said lip and on said other face, a central hub defining a suction cup extending into said recess portion but terminating short of the plane developed by said lip and an annular recessed hinged area at the base of said hub.

9. As an article of manufacture, a flexible key form made of rubber or the like, said form dening a substantially circular disk skived along its peripheral edge to form a truncated conical segment, said form further defining a plurality of V-shaped grooves arranged in spaced radial relationship to one another on one face of said disk, the apices of said grooves lying on a common circular axis on an inner portion of said form concentric with its periphery, said form including an angularly inclined conical lip on the opposite face of said form terminating in an inwardly disposed annular recess and a circular suction cup extending away from said annular recess', the lip of said suction cup terminating in substantial co-planar relation with the outermost portion of said lip, when said form is held on a flat surface by means of atmospheric air pressure, said key form being deformable within the limits prescribed by the hinging action of said annular recess and the contraction action of said V-shaped grooves.

10. A flexible key member for the liner surface of va mold form and adapted to shape a dovetail recess in a `mass of plastic aggregate hardened in the mold form and comprising a truncated conical body portion, a flexible lip on the body portion adapted to engage the liner surface of the mold form, said body portion having a recess interiorly of said lip, a hub forming a suction cup and extending into the recess, said suction cup terminating short of the plane normally developed by said lip, said body portion being made of a flexible material whereupon movement of said hub toward the liner surface of the mold form will flex said lip at the liner surface to form a curved recess, whereby the dove-tailed recesses formed in the plastic aggregate will have curved edge portions.

11. A exible key member according to claim 10 in which the body portion is provided with a plurality of radially spaced tongues and grooves to promote radial contractibility of the key form and to form radially spaced reinforcing ns in the dovetailed recesses.

l2. A flexible key member according to claim 10 in which a flexible hinge portion is situated between said hub and said body portion to permit flexure of the body portion about said hub upon withdrawal of the key member from the hardened plastic aggregate.

13. A key member according to claim 12 in which the body portion is provided with a plurality of radially spaced tongues and grooves to promote radial contractibility of the key member and to form reinforcing fins in the dovetailed recesses.

` ROBERT MAXWELL JAMES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,603,917 Johnston Oct. 19, 1926 1,641,147 Barton 1 Sept. 6, 1927 2,319,727 Duggan May 18. 1943 

